:root {
  --primary: #4F46E5;
  --primary-hover: #4338CA;
  --primary-light: #EEF2FF;
  --bg: #F8FAFC;
  --card: #FFFFFF;
  --text: #1E293B;
  --muted: #64748B;
  --border: #E2E8F0;
  --danger: #EF4444;
  --success: #10B981;
  --warning: #F59E0B;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.7;
  display: flex;
  flex-direction: column;
}

/* ===== NAV ===== */
.site-nav {
  background: #fff;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 1px 3px rgba(0,0,0,0.04);
}
.nav-inner {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}
.nav-brand {
  font-size: 18px;
  font-weight: 800;
  color: var(--primary);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 8px;
}
.nav-brand .icon { font-size: 22px; }
.nav-links { display: flex; gap: 6px; align-items: center; }
.nav-links a {
  text-decoration: none;
  font-size: 14px;
  font-weight: 500;
  color: var(--muted);
  padding: 6px 14px;
  border-radius: 8px;
  transition: all 0.2s;
}
.nav-links a:hover { color: var(--primary); background: var(--primary-light); }
.nav-links a.active { color: var(--primary); background: var(--primary-light); font-weight: 600; }

/* Mobile menu */
.nav-toggle { display: none; background: none; border: none; cursor: pointer; font-size: 24px; color: var(--text); padding: 4px; }
@media (max-width: 640px) {
  .nav-toggle { display: block; }
  .nav-links {
    display: none;
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    background: #fff;
    flex-direction: column;
    padding: 12px 20px;
    border-bottom: 1px solid var(--border);
    box-shadow: 0 4px 12px rgba(0,0,0,0.06);
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 10px 14px; }
}

/* ===== LAYOUT ===== */
.page-wrap {
  max-width: 900px;
  margin: 0 auto;
  padding: 24px 20px 48px;
  flex: 1;
  width: 100%;
}

/* ===== HERO ===== */
.hero {
  background: linear-gradient(135deg, #4F46E5 0%, #7C3AED 50%, #9333EA 100%);
  color: #fff;
  padding: 60px 20px 50px;
  text-align: center;
  border-radius: 0 0 24px 24px;
  margin-bottom: 32px;
}
.hero h1 {
  font-size: 36px;
  font-weight: 800;
  margin-bottom: 10px;
  letter-spacing: -1px;
}
.hero p {
  font-size: 16px;
  opacity: 0.85;
  max-width: 520px;
  margin: 0 auto;
  line-height: 1.6;
}
.hero .cta-btn {
  display: inline-block;
  margin-top: 24px;
  padding: 14px 36px;
  background: #fff;
  color: var(--primary);
  font-weight: 700;
  font-size: 16px;
  border-radius: 12px;
  text-decoration: none;
  transition: all 0.2s;
  box-shadow: 0 4px 16px rgba(0,0,0,0.15);
}
.hero .cta-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 24px rgba(0,0,0,0.2);
}

/* ===== FEATURES ===== */
.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 20px;
  margin: 32px 0;
}
.feature-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 24px;
  text-align: center;
  transition: box-shadow 0.2s;
}
.feature-card:hover { box-shadow: 0 4px 16px rgba(79,70,229,0.1); }
.feature-card .icon { font-size: 32px; margin-bottom: 12px; }
.feature-card h3 { font-size: 16px; font-weight: 700; margin-bottom: 6px; }
.feature-card p { font-size: 13px; color: var(--muted); line-height: 1.5; }

/* ===== CONTENT PAGE ===== */
.content-page {
  max-width: 760px;
  margin: 0 auto;
}
.content-page h1 {
  font-size: 28px;
  font-weight: 800;
  color: var(--text);
  margin-bottom: 8px;
}
.content-page .subtitle {
  font-size: 14px;
  color: var(--muted);
  margin-bottom: 32px;
}
.content-page h2 {
  font-size: 20px;
  font-weight: 700;
  color: var(--primary);
  margin-top: 36px;
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--primary-light);
}
.content-page h3 {
  font-size: 17px;
  font-weight: 600;
  margin-top: 24px;
  margin-bottom: 8px;
}
.content-page p {
  font-size: 15px;
  line-height: 1.8;
  margin-bottom: 16px;
  color: #374151;
}
.content-page ul, .content-page ol {
  margin: 0 0 16px 20px;
  font-size: 15px;
  line-height: 1.8;
  color: #374151;
}
.content-page li { margin-bottom: 6px; }
.content-page table {
  width: 100%;
  border-collapse: collapse;
  margin: 16px 0;
  font-size: 14px;
}
.content-page th, .content-page td {
  padding: 10px 12px;
  text-align: center;
  border-bottom: 1px solid var(--border);
}
.content-page th {
  background: #F1F5F9;
  font-weight: 600;
  color: var(--muted);
  font-size: 13px;
}
.content-page td { color: var(--text); }
.content-page .highlight-box {
  background: var(--primary-light);
  border-left: 4px solid var(--primary);
  padding: 16px 20px;
  border-radius: 0 10px 10px 0;
  margin: 20px 0;
  font-size: 14px;
}
.content-page .tip-box {
  background: #ECFDF5;
  border-left: 4px solid var(--success);
  padding: 16px 20px;
  border-radius: 0 10px 10px 0;
  margin: 20px 0;
  font-size: 14px;
}
.content-page .warn-box {
  background: #FFFBEB;
  border-left: 4px solid var(--warning);
  padding: 16px 20px;
  border-radius: 0 10px 10px 0;
  margin: 20px 0;
  font-size: 14px;
}

/* ===== FAQ ===== */
.faq-item {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  margin-bottom: 12px;
  overflow: hidden;
}
.faq-item summary {
  cursor: pointer;
  padding: 16px 20px;
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.faq-item summary::after { content: '+'; font-size: 20px; color: var(--muted); transition: transform 0.2s; }
.faq-item[open] summary::after { content: '−'; }
.faq-item .faq-answer {
  padding: 0 20px 16px;
  font-size: 14px;
  line-height: 1.8;
  color: #4B5563;
  border-top: 1px solid var(--border);
  padding-top: 14px;
}

/* ===== ARTICLE CARDS ===== */
.article-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 16px;
  margin: 24px 0;
}
.article-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px;
  text-decoration: none;
  transition: all 0.2s;
}
.article-card:hover {
  box-shadow: 0 4px 16px rgba(79,70,229,0.1);
  transform: translateY(-2px);
}
.article-card .tag {
  display: inline-block;
  background: var(--primary-light);
  color: var(--primary);
  font-size: 11px;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 20px;
  margin-bottom: 10px;
}
.article-card h3 { font-size: 16px; font-weight: 700; color: var(--text); margin-bottom: 6px; }
.article-card p { font-size: 13px; color: var(--muted); line-height: 1.5; }

/* ===== FOOTER ===== */
.site-footer {
  background: #1E293B;
  color: #94A3B8;
  padding: 40px 20px 24px;
  margin-top: auto;
}
.footer-inner {
  max-width: 900px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 32px;
}
@media (max-width: 640px) {
  .footer-inner { grid-template-columns: 1fr; gap: 20px; }
}
.footer-col h4 { font-size: 14px; font-weight: 700; color: #E2E8F0; margin-bottom: 12px; }
.footer-col a {
  display: block;
  font-size: 13px;
  color: #94A3B8;
  text-decoration: none;
  margin-bottom: 6px;
  transition: color 0.2s;
}
.footer-col a:hover { color: #F1F5F9; }
.footer-bottom {
  max-width: 900px;
  margin: 24px auto 0;
  padding-top: 20px;
  border-top: 1px solid #334155;
  text-align: center;
  font-size: 12px;
  color: #64748B;
}

/* ===== BREADCRUMB ===== */
.breadcrumb {
  font-size: 13px;
  color: var(--muted);
  margin-bottom: 20px;
}
.breadcrumb a { color: var(--primary); text-decoration: none; }
.breadcrumb a:hover { text-decoration: underline; }
.breadcrumb .sep { margin: 0 6px; }

/* ===== CONTACT PAGE ===== */
.contact-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
  margin: 20px 0;
}
.contact-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  text-align: center;
}
.contact-card .contact-icon { font-size: 32px; margin-bottom: 10px; }
.contact-card h3 { font-size: 16px; font-weight: 700; margin-bottom: 6px; }
.contact-card p { font-size: 14px; color: var(--muted); margin-bottom: 4px; }
.contact-card .contact-note { font-size: 12px; color: #94A3B8; }

.contact-form {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 28px;
  margin: 20px 0;
}
.form-group {
  margin-bottom: 18px;
}
.form-group label {
  display: block;
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 6px;
  color: var(--text);
}
.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: 10px;
  font-size: 14px;
  color: var(--text);
  background: #F8FAFC;
  transition: border-color 0.2s;
  font-family: inherit;
}
.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(79,70,229,0.1);
}
.btn-primary {
  background: var(--primary);
  color: #fff;
  border: none;
  padding: 12px 32px;
  font-size: 15px;
  font-weight: 600;
  border-radius: 10px;
  cursor: pointer;
  transition: all 0.2s;
}
.btn-primary:hover { background: var(--primary-hover); transform: translateY(-1px); }

/* ===== FEATURES GRID (about page) ===== */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 16px;
  margin: 20px 0;
}
.features-grid .feature-card { text-align: center; }
.features-grid .feature-icon { font-size: 28px; margin-bottom: 8px; }

/* ===== TIMELINE (about page) ===== */
.timeline {
  position: relative;
  padding: 10px 0 10px 28px;
  margin: 16px 0;
  border-left: 3px solid var(--primary);
}
.timeline-item {
  position: relative;
  margin-bottom: 20px;
  padding-left: 16px;
}
.timeline-item::before {
  content: '';
  position: absolute;
  left: -36px;
  top: 6px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--primary);
  border: 2px solid #fff;
  box-shadow: 0 0 0 2px var(--primary);
}
.timeline-date {
  font-weight: 700;
  color: var(--primary);
  font-size: 14px;
  margin-bottom: 4px;
}
.timeline-content {
  font-size: 15px;
  line-height: 1.6;
  color: #444;
}

/* ===== CONTACT CARDS ===== */
.contact-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  margin: 20px 0;
}
.contact-card {
  background: var(--bg-light, #f8f9ff);
  border-radius: 12px;
  padding: 20px;
  text-align: center;
  border: 1px solid var(--border, #e2e8f0);
  transition: transform 0.2s;
}
.contact-card:hover { transform: translateY(-2px); }
.contact-icon { font-size: 32px; margin-bottom: 8px; }
.contact-note { font-size: 13px; color: #888; margin-top: 6px; }

/* ===== CONTACT FORM ===== */
.contact-form {
  background: var(--bg-light, #f8f9ff);
  border-radius: 12px;
  padding: 24px;
  margin: 20px 0;
  border: 1px solid var(--border, #e2e8f0);
}
.form-group {
  margin-bottom: 16px;
}
.form-group label {
  display: block;
  font-weight: 600;
  margin-bottom: 6px;
  font-size: 14px;
}
.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 10px 14px;
  border: 1px solid var(--border, #e2e8f0);
  border-radius: 8px;
  font-size: 15px;
  font-family: inherit;
  background: #fff;
  box-sizing: border-box;
}
.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 2px rgba(99,102,241,0.15);
}
.form-group textarea { resize: vertical; min-height: 100px; }